Montana's Prairie Stream Surveys Begin To Solve A Mystery

Ken McDonald, Montana FWP Fisheries Division Special Projects Bureau Chief

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There are about 18,000 miles of prairie streams in Montana but few state fisheries biologists could say for certain what’s in them.

The contents of these 4,200 warm water prairie streams were only an educated guess until this summer when Montana Fish, Wildlife & Parks fisheries crews began to survey these waters.

FWP randomly selected 305 sites in 240 drainages in the Great Falls, Billings, Glasgow and Miles City areas this summer. It wasn’t unusual for the crews to find little water in some streams or no fish. But at 122 sites with both fish and water, FWP crews collected valuable data that will begin to help biologists better understand Montana’s vast prairie ecosystem.  

Funding for the stream survey work comes from the federal State Wildlife Grant program, a temporary funding program that many hope will become a permanent offering for fish and wildlife conservation. Survey teams were hired for 4-6 months to range over huge expanses of eastern Montana prairie. Each study focused on a 300-meter stretch, a length slightly longer than a football field.

First the site was logged into a Global Positioning System for an exact geographic location for future reference. Then the teams used fine nets to pull all of the fish out of a reach of stream to identify, measure and count them before releasing them again. In a few cases, unusual specimens were preserved for additional study to ensure they are being accurately identified.  

The depth and width of the water and water quality were measured and the materials on the bottom were examined.  

In all, FWP examined 39,827 individual fish and identified up to 10 different species at the average site. Most of these fish were “minnows” or small species with catchy names like the brook stickleback, goldeye, emerald shiner, shorthead redhorse and sand shiner. A total of 32 different species were encountered during the summer and 25 of them were native to Montana.

What good are these mini-fish and why care about them? While they are not the typical sport fish, they are valuable components of the prairie ecosystem and an important food source for sport fish such as sauger, pike and walleye, as well as for herons, king fishers and other opportunistic predators.

These species are well adapted to the warm, muddy, boom-and-bust conditions of the prairie, with unique adaptations that allow them to survive.

Caring about these tiny fish makes us more aware of their habitat, too. A prairie stream that is dry in August may be important for spawning when it is flowing with spring runoff.

If a dry wash is viewed as having value as a fishery, a needed local improvement such as a road crossing might be built in a way that meets the community’s needs and retains access for fish for spawning in the wet parts of the year.

In addition, the information we’re gathering will contribute to understanding how the life-cycle of these prairie minnows affect the larger, more popular species that depend on them.